Bump up version number for release

For reference, some benchmarks -- though not from v1.24.0 to v1.25.0
(that delta is insignificant), but from Go 1.20 to Go 1.21. The latter
is almost 10% faster overall, even without PGO:

name                     old time/op  new time/op  delta
ForInLoop-16             1.07µs ± 3%  1.61µs ± 2%  +50.77%  (p=0.008 n=5+5)
BuiltinSplitSpace-16     22.9µs ± 3%  23.1µs ± 1%     ~     (p=0.690 n=5+5)
BuiltinSub-16            7.88µs ± 4%  7.66µs ± 3%     ~     (p=0.151 n=5+5)
BuiltinSubAmpersand-16   8.03µs ± 3%  7.71µs ± 5%     ~     (p=0.095 n=5+5)
BuiltinGsub-16           10.0µs ±13%   9.3µs ± 2%     ~     (p=0.056 n=5+5)
BuiltinGsubAmpersand-16  9.56µs ± 3%  9.46µs ± 3%     ~     (p=0.222 n=5+5)
BuiltinSprintf-16        5.26µs ± 2%  5.12µs ± 3%     ~     (p=0.056 n=5+5)
GetField-16               215ns ± 5%   206ns ± 4%     ~     (p=0.095 n=5+5)
ConcatLarge-16           1.41ms ± 6%  1.23ms ±15%     ~     (p=0.056 n=5+5)
RepeatExecProgram-16     10.8µs ± 5%  10.3µs ± 2%     ~     (p=0.056 n=5+5)
RepeatIOExecProgram-16   23.6µs ± 5%  23.3µs ± 2%     ~     (p=1.000 n=5+5)
CSVInputGoAWK-16          253ns ±11%   256ns ±13%     ~     (p=1.000 n=5+5)
CSVInputReader-16         167ns ±15%   163ns ±10%     ~     (p=1.000 n=5+5)
CSVOutputGoAWK-16         275ns ±13%   275ns ± 4%     ~     (p=0.421 n=5+5)
CSVOutputWriter-16        177ns ± 3%   176ns ± 3%     ~     (p=1.000 n=5+5)
SimplePattern-16         91.8ns ± 3%  88.6ns ± 2%   -3.55%  (p=0.032 n=5+5)
Printf-16                2.71µs ± 3%  2.60µs ± 2%   -3.90%  (p=0.008 n=5+5)
BuiltinSplitRegex-16     53.6µs ± 7%  51.3µs ± 1%   -4.34%  (p=0.016 n=5+5)
Print-16                 1.23µs ± 3%  1.17µs ± 2%   -4.93%  (p=0.008 n=5+5)
BuiltinMatch-16          1.51µs ± 1%  1.43µs ± 2%   -5.24%  (p=0.008 n=5+5)
SimpleBuiltins-16         394ns ± 2%   366ns ± 4%   -6.97%  (p=0.008 n=5+5)
SetField-16               545ns ± 2%   501ns ± 3%   -7.99%  (p=0.008 n=5+5)
AugAssign-16              598ns ± 4%   546ns ± 4%   -8.62%  (p=0.008 n=5+5)
BuiltinIndex-16           662ns ± 4%   604ns ± 4%   -8.73%  (p=0.008 n=5+5)
RepeatIONew-16            692ns ± 1%   626ns ± 3%   -9.49%  (p=0.008 n=5+5)
BuiltinLength-16          310ns ± 3%   278ns ± 5%  -10.33%  (p=0.008 n=5+5)
BuiltinSubstr-16          514ns ± 3%   449ns ± 6%  -12.65%  (p=0.008 n=5+5)
RegexMatch-16             684ns ± 5%   594ns ± 4%  -13.04%  (p=0.008 n=5+5)
NativeFunc-16            6.72µs ± 4%  5.76µs ± 3%  -14.23%  (p=0.008 n=5+5)
RecursiveFunc-16         8.71µs ± 6%  7.45µs ± 3%  -14.41%  (p=0.008 n=5+5)
CondExpr-16              94.5ns ± 4%  80.8ns ± 3%  -14.48%  (p=0.008 n=5+5)
FuncCall-16              1.59µs ± 4%  1.32µs ± 5%  -17.07%  (p=0.008 n=5+5)
ConcatSmall-16            245ns ± 5%   202ns ± 3%  -17.73%  (p=0.008 n=5+5)
RepeatNew-16             72.3ns ± 4%  59.5ns ± 3%  -17.73%  (p=0.008 n=5+5)
ArrayOperations-16        361ns ± 5%   295ns ± 5%  -18.36%  (p=0.008 n=5+5)
ForLoop-16               1.77µs ± 4%  1.44µs ± 5%  -18.67%  (p=0.008 n=5+5)
IfStatement-16           98.7ns ± 1%  79.8ns ± 5%  -19.15%  (p=0.008 n=5+5)
Comparisons-16            267ns ± 4%   215ns ± 3%  -19.48%  (p=0.008 n=5+5)
ConcatTwo-16             62.4ns ± 4%  50.1ns ± 3%  -19.67%  (p=0.008 n=5+5)
IncrDecr-16               114ns ± 4%    91ns ± 3%  -20.04%  (p=0.008 n=5+5)
Assign-16                 172ns ± 4%   137ns ± 3%  -20.05%  (p=0.008 n=5+5)
GlobalVars-16             176ns ± 4%   136ns ± 5%  -23.21%  (p=0.008 n=5+5)
LocalVars-16              173ns ± 5%   128ns ± 4%  -26.31%  (p=0.008 n=5+5)
BinaryOperators-16        358ns ± 5%   249ns ± 6%  -30.50%  (p=0.008 n=5+5)
[Geo mean]                992ns        894ns        -9.82%

And scripts/benchmark_awks.py:

goawk=go1.21.0 (without PGO)
orig =go1.20.6 (without PGO)

Test                         |    goawk |     orig |      awk
---------------------------- | -------- | -------- | --------
tt.01 (print)                |     2.71 |     2.74 |     1.00
tt.02 (print NR NF)          |     2.07 |     2.01 |     1.00
tt.02a (print length)        |     1.78 |     1.76 |     1.00
tt.03 (sum length)           |     1.47 |     1.43 |     1.00
tt.03a (sum field)           |     1.50 |     1.47 |     1.00
tt.04 (printf fields)        |     1.25 |     1.22 |     1.00
tt.05 (concat fields)        |     1.57 |     1.43 |     1.00
tt.06 (count lengths)        |     1.57 |     1.59 |     1.00
tt.07 (even fields)          |     1.54 |     1.49 |     1.00
tt.08 (even lengths)         |     2.37 |     2.27 |     1.00
tt.08z (regex simple)        |     4.00 |     3.75 |     1.00
tt.09 (regex starts with)    |     2.59 |     2.61 |     1.00
tt.10 (regex ends with)      |     0.44 |     0.44 |     1.00
tt.10a (regex ends with var) |     0.44 |     0.44 |     1.00
tt.11 (substr)               |     3.18 |     3.08 |     1.00
tt.12 (update fields)        |     1.48 |     1.43 |     1.00
tt.13 (array ops)            |     4.02 |     3.71 |     1.00
tt.13a (array printf)        |     2.98 |     2.63 |     1.00
tt.14 (function call)        |     1.58 |     1.31 |     1.00
tt.15 (format lines)         |     0.93 |     0.83 |     1.00
tt.16 (count words)          |     1.83 |     1.62 |     1.00
tt.big (complex program)     |     2.16 |     1.98 |     1.00
tt.x1 (mandelbrot)           |     2.53 |     1.92 |     1.00
tt.x2 (sum loop)             |     2.16 |     1.71 |     1.00
---------------------------- | -------- | -------- | --------
**Geo mean**                 | **1.77** | **1.65** | **1.00**

Author: benhoyt

goawk.go

@@ -47,7 +47,7 @@ import (
 )
 
 const (
-	version    = "v1.24.0"
+	version    = "v1.25.0"
 	copyright  = "GoAWK " + version + " - Copyright (c) 2022 Ben Hoyt"
 	shortUsage = "usage: goawk [-F fs] [-v var=value] [-f progfile | 'prog'] [file ...]"
 	longUsage  = `Standard AWK arguments: